The invention relates to a vehicle propulsion system which comprises an electrical drive motor and a fuel cell that provides the electric power.
It is known from European Patent Document EP 1 266 783 E1 to decouple the fuel cell and the drive motor by suitable vibration dampers in a vehicle which is driven by a fuel cell system. The flexible electrical connections which are required between the fuel cell, the drive motor (and optionally the converter) have proved to be disadvantageous in such structures, in particular due to the very high currents and/or voltages involved. Adequate reliability of the connections entails highly complex production and installation methods, as stringent requirements apply to flexibility, watertightness and electromagnetic compatibility (EMC).
One object of the invention is to provide a simple, compact vehicle propulsion structure which can be constructed inexpensively and reliably and which permits simple installation.
This and other objects and advantages are achieved by the vehicle propulsion system according to the invention, in which the fuel cell and the electrical drive motor are integrated into a single unit and firmly joined together. In contrast to the prior art, “firmly” in this case means not decoupled; thus for example they may be joined by a direct screw joint, for example to a common supporting structure.
The integration of the fuel cell and drive motor as a unit reduces the costs, mass and volume of the unit. Moreover, previous systems have required complex (and thus costly) cables and connectors to provide in particular electrical connection between the fuel cell and ensure electromagnetic compatibility (EMC). Such cables and connectors may be dispensed with thanks to integration as a unit. In addition to the advantages with regard to costs and installation space, dispensing with connections and cabling which must be constructed flexibly means that reliability may be increased.
Furthermore, integration as a unit also permits improved, lighter, faster (and thus also more inexpensive) installation. Integration as a unit may readily be achieved by preassembly outside the vehicle, and the preassembled unit may then simply be installed in the vehicle (for example in the engine compartment in place of a combustion engine), and then connected with the drive shafts, media supplies etc.
The centralized location of system masses in the integrated unit has a positive impact on acoustic characteristics and more effective damping of the overall unit may be provided. The structure according to the invention thus also achieves advantages in the efficient implementation of NVH (noise, vibration, harshness) measures.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.